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xpt - CAM transport layer interface
The xpt driver provides a way for userland applications to issue certain
CAM CCBs to the kernel.
Since the xpt driver allows direct access to the CAM subsystem, system
administrators should exercise caution when granting access to this
driver. If used improperly, this driver can allow userland applications
to crash a machine or cause data loss.
There is no kernel configuration required for the xpt driver. It is
enabled when SCSI support is enabled in the kernel. There is one
instance of the xpt driver per CAM transport layer instance. Since there
is currently only one CAM transport layer, there will only be one
instance of this driver.
CAMIOCOMMAND This ioctl takes certain kinds of CAM CCBs and passes
them through to the CAM transport layer for action. Only
the following CCB types are supported:
The above CCBs are the only ones supported since it makes
more sense to send them through a generic passthrough
device rather than a passthrough device tied to a
particular underlying SCSI device.
CAMGETPASSTHRU This ioctl takes an XPT_GDEVLIST CCB, and returns the
passthrough device corresponding to the device in
/dev/xpt0 Character device node for the xpt driver.
cam(3), cam_cdbparse(3), pass(4), camcontrol(8)
The CAM transport layer driver first appeared in FreeBSD 3.0.
Kenneth Merry 〈ken@FreeBSD.org〉